Utah Standards
Maximum concentration in drinking water: 10 mg/L

Greater than 4 mg/L in surface water indicates pollution

There are two main groups of nitrogen, organic and inorganic. Organic nitrogen includes all of the nitrogen that is part of living animals, animal wastes and the remains of living things. Organic forms of nitrogen must be broken down into inorganic forms in order to be used by plants. Examples of inorganic nitrogen are N2, N03, NH3, N02. Nitrate (N03) is the most common form of inorganic nitrogen found in waterways. Plants can directly use this form of nitrogen to build proteins.

Natural influences that cause nitrogen concentrations to change in water: Human influences that cause nitrogen concentrations to change in water:
Seasonal changes:
  • In Utah concentrations are usually highest in the springtime when runoff from melting snow carries nutrients from lawns, farms and other areas into the water. Many people in Utah get their culinary water from groundwater from cities or private wells. Groundwater has naturally higher concentrations of nitrate.
  • Plant uptake-during the spring and summer months plants grow causing concentrations of nitrates to be low during this time. In the winter and fall, when plants stop growing and die, much of the nitrogen is released into the water again, increasing the nitrogen concentration.
  • fertilizers
  • livestock manure
  • malfunctioning septic systems
  • discharge from sewage facilities
  • acid precipitation

Why care about nitrogen?


When waterways become over fertilized with nitrogen there can be heavy plant growth. Excessive plant growth can decrease the aesthetic value of the water because of the smelly decomposing mats of vegetation. Also, when bacteria decompose dead plant material they use up dissolved oxygen which is important for the survival of macroinvertebrates and other aquatic organisms.

Human Health

High concentrations of nitrate in drinking water can cause methemoglobinemia (also known as blue baby syndrome). Concentrations greater than 10 parts per million can be harmful to young babies, and should be avoided by nursing mothers. Find out more about nitrate.

Livestock Health

Concentrations of nitrate over 100 parts per million are toxic to livestock. Nitrates are odorless, colorless, and tasteless so it is important to test feed and drinking water to determine levels of nitrate.
Find out more about nitrate.

What is being done to minimize nitrogen related problems?
Nutrient Pollution Policy and Data

Nitrogen Cycle (for more information click here)

For more information see Understanding Your Watershed: Nitrogen.


Utah Standards
Concentrations of 0.05mg/L or above in a stream or river indicates pollution.

Concentrations of 0.025mg/L or above in a lake indicates pollution.

Phosphorus is an important nutrient for plants. Phosphorus, like nitrogen, can be found in multiple forms in the environment. Unlike nitrogen, phosphorus moves very slowly through the environment. It is mostly tied up in rocks and minerals. There are two main forms of Phosphorus, organic and inorganic. Organic phosphorus includes all the phosphorus found in living or dead animals and plants as well as their wastes. When animals and plants decay dissolved phosphorus is often released. Microorganisms must break this form of phosphorus in order for plants to use it. Most phosphorus is in an inorganic form in minerals, rocks and soils. Plants can easily use this form of phosphorus (called orthophosphate). However, it is often scarce in water and limits plant growth in streams and lakes. One reason orthophosphate is scarce in water is because it easily attaches to sediment particles and settles out.

Natural influences that cause phosphorus concentrations to change in water: Human influences that cause phosphorus concentrations to change in water:
  • Seasons-during spring runoff (or when flows are high) sediment concentrations can be high. Phosphorus attaches to sediment, so this may cause the water to have a higher concentration of phosphorus as well.
  • logging
  • building activities
  • overgrazing in riparian zone
  • removal of riparian vegetation
  • runoff from fertilizers
  • poorly functioning septic tanks
  • waste management treatment plants

Why care about phosphorus?

Phosphorus is often the nutrient that limits how much plant growth occurs in a stream, lake or reservoir. Therefore, adding a small amount of phosphorus may cause excess plant growth. When these plants die, huge mats of decaying plants create odor and aesthetic problems. When the plants in lakes and reservoirs die, more oxygen may be used in the decomposition process than can be replaced. Without sufficient oxygen fish and macroinvertebrates will die. Also, certain types of microscopic algae can be toxic if they reach very high concentrations. Animals such as dogs or livestock that drink from these toxic water bodies can become sick or die.

What is being done to minimize phosphorus related problems? Nutrient Pollution Policy and Data

Phosphorus Cycle


For more information see Understanding Your Watershed: Phosphorus.